- published: 20 Apr 2016
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Evolution is any change across successive generations in the inherited characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.
Life on Earth originated and then evolved from a universal common ancestor approximately 3.7 billion years ago. Repeated speciation and the divergence of life can be inferred from shared sets of biochemical and morphological traits, or by shared DNA sequences. These homologous traits and sequences are more similar among species that share a more recent common ancestor, and can be used to reconstruct evolutionary histories, using both existing species and the fossil record. Existing patterns of biodiversity have been shaped both by speciation and by extinction.
Charles Darwin was the first to formulate a scientific argument for the theory of evolution by means of natural selection. Evolution by natural selection is a process that is inferred from three facts about populations: 1) more offspring are produced than can possibly survive, 2) traits vary among individuals, leading to differential rates of survival and reproduction, and 3) trait differences are heritable. Thus, when members of a population die they are replaced by the progeny of parents that were better adapted to survive and reproduce in the environment in which natural selection took place. This process creates and preserves traits that are seemingly fitted for the functional roles they perform. Natural selection is the only known cause of adaptation, but not the only known cause of evolution. Other, nonadaptive causes of evolution include mutation and genetic drift.
William Sanford "Bill" Nye (born November 27, 1955), popularly known as Bill Nye the Science Guy, is an American science educator, comedian, television host, actor, mechanical engineer, and scientist. He is best known as the host of the Disney/PBS children's science show Bill Nye the Science Guy (1993–1998) and for his many subsequent appearances in popular media as a science educator.
William Sanford Nye was born in Washington, D.C., the son of Jacqueline (née Jenkins; c. 1920–2000), a codebreaker during World War II, and Edwin Darby "Ned" Nye (died 1997), also a World War II veteran whose experience in a Japanese prisoner of war camp led him to become a sundial enthusiast. Nye is a fourth-generation Washington, D.C. resident on his father's side of the family. After attending Lafayette Elementary and Alice Deal Junior High in the city, he was accepted to the private Sidwell Friends School on a partial scholarship, graduating in 1973. He studied mechanical engineering at Cornell University, where one of his professors was Carl Sagan, and graduated with a Bachelor of Science in 1977. He was awarded an honorary doctorate by The Johns Hopkins University in May 2008. In May 2011, Nye was awarded an Honorary Doctor of Science degree from Willamette University where he was the keynote speaker for that year's commencement exercises.
Michael Jeffrey Jordan (born February 17, 1963) is a retired American professional basketball player, active entrepreneur, and majority owner of the Charlotte Bobcats. His biography on the National Basketball Association (NBA) website states, "By acclamation, Michael Jordan is the greatest basketball player of all time." Jordan was one of the most effectively marketed athletes of his generation and was considered instrumental in popularizing the NBA around the world in the 1980s and 1990s.
After a three-season career at the University of North Carolina at Chapel Hill, where he was a member of the Tar Heels' national championship team in 1982, Jordan joined the NBA's Chicago Bulls in 1984. He quickly emerged as a league star, entertaining crowds with his prolific scoring. His leaping ability, illustrated by performing slam dunks from the free throw line in slam dunk contests, earned him the nicknames "Air Jordan" and "His Airness". He also gained a reputation for being one of the best defensive players in basketball. In 1991, he won his first NBA championship with the Bulls, and followed that achievement with titles in 1992 and 1993, securing a "three-peat". Although Jordan abruptly retired from basketball at the beginning of the 1993–94 NBA season to pursue a career in baseball, he rejoined the Bulls in 1995 and led them to three additional championships (1996, 1997, and 1998) as well as an NBA-record 72 regular-season wins in the 1995–96 NBA season. Jordan retired for a second time in 1999, but returned for two more NBA seasons from 2001 to 2003 as a member of the Washington Wizards.